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A widow's peak is a distinct point in the hairline in the center of the forehead; [1] there are varying degrees of the peak. Although it is commonly taught as an example of a dominant inherited trait , [ 2 ] [ 3 ] there are no scientific studies to support this.
Autosomal dominant A 50/50 chance of inheritance. Sickle-cell disease is inherited in the autosomal recessive pattern. When both parents have sickle-cell trait (carrier), a child has a 25% chance of sickle-cell disease (red icon), 25% do not carry any sickle-cell alleles (blue icon), and 50% have the heterozygous (carrier) condition. [1]
Offspring with either one or two copies of the dominant allele will display the dominant phenotype. Very few phenotypes are purely Mendelian traits. Common violations of the Mendelian model include incomplete dominance , codominance , genetic linkage , environmental effects , and quantitative contributions from a number of genes (see: gene ...
Four different traits can be identified by pedigree chart analysis: autosomal dominant, autosomal recessive, x-linked, or y-linked. Partial penetrance can be shown and calculated from pedigrees. Penetrance is the percentage expressed frequency with which individuals of a given genotype manifest at least some degree of a specific mutant ...
People with Aarskog–Scott syndrome often have distinctive facial features, such as widely spaced eyes (hypertelorism), a small nose, a long area between the nose and mouth , and a widow's peak hairline. They frequently have mild to moderate short stature during childhood, but their growth usually catches up with that of their peers during ...
Pure consideration of alleles is often referred to as Mendelian Genetics, or more properly Classical Genetics, and involves the assessment of whether a given trait is dominant or recessive and thus, at what rates it will be inherited. [9] The color of one's eyes was long believed to occur with a pattern of brown-eye dominance, with blue eyes ...
Oligogenic inheritance (Greek ὀλίγος – ὀligos = few, a little) describes a trait that is influenced by a few genes. Oligogenic inheritance represents an intermediate between monogenic inheritance in which a trait is determined by a single causative gene, and polygenic inheritance, in which a trait is influenced by many genes and often environmental factors.
This disorder is characterized by unusual facial features, including prominent, wide-set eyes with outer corners that point downward; a short bulbous nose with a flat nasal bridge; ears that are rotated backward; and a widow's peak hairline.